CDK5-dependent phosphorylation of the Rho family GTPase TC10(alpha) regulates insulin-stimulated GLUT4 translocation.
Insulin stimulation results in the activation of cyclin-dependent kinase-5 (CDK5) in lipid raft domains via a Fyn-dependent phosphorylation on tyrosine residue 15. In turn, activated CDK5 phosphorylates the Rho family GTP-binding protein TC10alpha on threonine 197 that is sensitive to the CDK5 inhibitor olomoucine and blocked by small interfering RNA-mediated knockdown of CDK5. The phosphorylation deficient mutant T197A-TC10alpha was not phosphorylated and excluded from the lipid raft domain, whereas the phosphorylation mimetic mutant (T197D-TC10alpha) was lipid raft localized. Insulin resulted in the GTP loading of T197D-TC10alpha but not T197A-TC10alpha and in parallel, T197D-TC10alpha but not T197A-TC10alpha depolymerized cortical actin and inhibited insulin-stimulated GLUT4 translocation. These data demonstrate that CDK5-dependent phosphorylation maintains TC10alpha in lipid raft compartments thereby disrupting cortical actin, whereas subsequent dephosphorylation of TC10alpha through inactivation of CDK5 allows for the re-assembly of F-actin. Because cortical actin reorganization is required for insulin-stimulated GLUT4 translocation, these data are consistent with a CDK5-dependent TC10alpha cycling between lipid raft and non-lipid raft compartments.
Okada
Shuichi
S
Department of Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma 371-0034, Japan. okadash@showa.gunma-u.ac.jp
Yamada
Eijiro
E
Saito
Tsugumichi
T
Ohshima
Kihachi
K
Hashimoto
Koshi
K
Yamada
Masanobu
M
Uehara
Yutaka
Y
Tsuchiya
Takafumi
T
Shimizu
Hiroyuki
H
Tatei
Kazuaki
K
Izumi
Takashi
T
Yamauchi
Keishi
K
Hisanaga
Shin-Ichi
S
Pessin
Jeffrey E
JE
Mori
Masatomo
M
D041721:3T3-L1 Cells; D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D007701:Kinetin / Q000494:pharmacology; D021962:Membrane Microdomains / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D004791:Enzyme Inhibitors; D051275:Glucose Transporter Type 4; D007328:Insulin; D034741:RNA, Small Interfering; C495693:Slc2a4 protein, mouse; C090046:olomoucine; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D051360:Cyclin-Dependent Kinase 5; C495906:Cdk5 protein, mouse; C503260:Rhoq protein, mouse; D020741:rho GTP-Binding Proteins; D007701:Kinetin